Press for vulcanizing mechanical articles



L. E. SODERQUIST PRESS FOR VULCANIZING MECHANICAL ARTICLES July 3, 1951Filed Feb. 6. 1947 11 Sheets-Sheet 1 1654/65 JOQEQU/ST ATTORNEY:

July 3, 1951 L. E. SODERQUIST PRESS FOR VULCANIZING MECHANICAL ARTICLES11 Sheets-Sheet 2 Filed Feb. 6, 1947 INVENTOR ZffZ/fff meal/1.5T

ATTORNEY$ July 3, 1951 E. SODERQUIST PRESS FOR VULCANIZING MECHANICALARTICLES Fi ied Feb. 6, 1947 ll Sheets-Sheet 5 INVENTOR 1554/5550956120467 ATTORNEYS July 3, 1951 L. E. SODERQUIST PRESS FORVULCANIZING MECHANICAL ARTICLES 11 Sheets-Sheet 4 Filed Feb. 6, 1947 oxowng \QQQ ////////////4 o ATTORN 5Y5 y 1951 L. E. SODERQUIST 2,559,377

PRESS FOR VULCANIZING MECHANICAL ARTICLES Filed Feb. 6, 1947 llSheets-Sheet 5 INVENTOR ATTO NEYa L. E. SODERQUIST PRESS FOR VULCANIZINGMECHANICAL ARTICLES July 3, 1951 Filed Feb. 6, 1947 ll Sheets-Sheet 6INVENTOR ATTORNEYS July 3, 1951 E. SODERQUIST PRESS FOR VULCANIZINGMECHANICAL ARTICLES 11 Sheets-Sheet 7 Filed Feb. 6, 1947 INVENTOR 554/456U562Ul57 r5 ATTO RN EYS July 3, 1951 E. SODERQUIST PRESS FORVULCANIZING MECHANICAL ARTICLES Filed Feb. 6, 1947 ll Sheets-Sheet 8srdP 2/1040 o b4? w OPE/V Fauna UP W Cut/N6 PIE/o0 BY f ATTO RN EYE)July 3, 1951 L. E. SODERQUIST 2,559,377

PRESS FOR VULCANIZING MECHANICAL ARTICLES Filed Feb. 6, 1947 11Sheets-Sheet 9 E6. I INVENTOR ATTORNEYS July 3, 1951 E. SODERQUIST2,559,377

PRESS FOR VULCANIZING MECHANICAL ARTICLES .Filed Feb. 6, 1947 llSheets-Sheet l0 INVENTOR Z A ORNE July 3, 1951 L. E. SODERQUIST2,559,377

PRESS FOR VULCANIZING MECHANICAL ARTICLES Filed Feb. 6, 1947 llSheets-Sheet ll 1f AT OWE 3:

Patented July 3, 1951 PRESS FOR VULCANIZING MECHANICAL ARTICLES LeslieE. Soderquist, Akron, Ohio, assignor to The McNeil Machine andEngineering Company, Akron, Ohio, a corporation of Ohio ApplicationFebruary 6, 1947, Serial No. 726,912

12 Claims.

This invention has for its object the designing of a pratcical,mechanically operated press primarily intended for the vulcanization ofarticles known in the art as mechanical goods. This expression covers anextensive variety of articles such as rubber heels, soles, rubberautomobile fittings and also hard rubber goods of all types. Articles ofthis type are vulcanized in molds under pressure exerted by the pressand it is quite common to employ molds having multiple cavities so thata multiplicity of the articles can be cured at one time.

These goods are usually made of uncured stocks which at roomtemperatures are comparatively stiff and unyielding. The stock isgenerally died out in rough blanks of a volume approximating the volumeof a mold cavity, but with very little effort to approach the shape ofthe cavity. These stocks will soften under the heat of vulcanization andwill ultimately flow under heat and pressure so as to fill out thecavities.

Due to the foregoing, it has heretofore been the practice to employhydraulically-actuated presses in the vulcanization of goods of thischaracter because the hydraulic pressure acts to follow-up the molds asthe stock gradually softens, and although the mold may not closecompletely at the start of the operation, as the stocks soften the moldis brought to a complete closed condition by the continuing pressureexerted by the hydraulic ram.

This distinctive action of mechanical goods stocks has made itimpractical heretofore to employ mechanically operated presses in thisparticular field. Hydraulic presses have many disadvantages, one of theprincipal ones being the difliculty in making the rams and connectionsleakproof. A press room equipped with hydraulic presses is always messy,in addition to which the pressure apparatus requires extensivesupervision and maintenance.

A mechanically operated press which would be adaptable for this type ofwork would obviate many of the troubles and inconveniences attendantupon the manufacture of mechanical goods. The difficulty in adaptingmechanically operated presses, such as used in the vulcanization of tirecasings, to the field of mechanical goods, is that the press operatingmechanisms have fixed cycles which bring the mold sections to the finalclosed position at the end of each closing movement. Whenever a press ofthis type has been used in the production of mechanical goods it hasbeen found that the resistance of the stock would either stall the pressbefore the molds were closed or so great a strain would be placed on theoperthe 'is equipped with a control and operating mechanism which willbring the press to a stop on its closing movement when the resistanceset up by the stock reaches a predetermined limit.

One of the objects of the invention is to provide means responsive tothe stresses created in closing the press which will stop the closingmovement when'the resistance reaches the predetermined limit.

The complete press shown and described is equipped with meanswhich, asthe stock softens and the stresses recede, causes the press to resumeits closing movement. This causes the press to close in a series ofsteps with the softening of the stock.

The complete follow up is accomplished by providing reacting meansresponsive to the strain on the press members which arrests the closingoperation before the resistance of the stock becomes so great as toendanger the press. As the resistance lowers due to the softening of thestock, the strain responsive means is relaxed and the press closingmechanism is again setin motion until the resistance causes theresponsive means to re-arrest the closing operation.

The mechanism shown and described herein accomplishes a still furtherpurpose peculiar to this type of molding. stocks for mechanical goodsand hard rubber stocks give off gases while being cured, and it isadvisable to open the mold slightly, particularly during the early partof the cure, to permit these gases to escape from the mold cavities.This operation of opening the molds momentarily is known in the trade asbumping. The mechanism shown herein causes the mold to separate slightlyafter the mold is fully closed, as many times as may be necessary torelease the gas entrapped within the mold.

lit is a further object of the invention to provide a press of this typewhich will facilitate'the removal of the finished goods and thepreparation of the molds for the next operation. Frequently the goodswill stick in the upper mold section and have to be removed therefrombythe operator. The press shown herein is provided with means by whichthe upper mold section automatically drops at apcint in advance of thefully opened position so that the upper mold section is presented at aconvenient angle to the 3 operator so that he can pick out any articleswhich have stuck in the upper mold section and swab the mold surfacewith the cleaning and lubricating compound. The press stops at thisposition on the opening movement, and when the operator has removed anycured goods adhering to the upper mold section and prepared the moldsurfaces, he presses a button and the press moves to its fully openedposition, the upper mold section being raised so that it is wholly outof the way and does not interfere with the loading and lubricating ofthe lower mold section for the next curing cycle.

The above are the principal objectives of the improved pressconstruction shown and described herein, although other advantages willbe attained as will be understood as the description proceeds. the pressis designed primarily for the vulcanization of rubber goods, it is notlimited to this particular branch of the plastic molding industry andmay be used for the molding of other types of plastics.

The mechanism shown and described is the best known and. preferred formof the invention, but this is not intended as limiting the scope of theinvention to this embodiment, as modifications and variations may beadopted. As one modification it is possible to dispense with the followup and bymerely combining the safety feature which will arrest the presswhen. the stresses reach a dangerous point with the bumping feature thepress may be successfully used in the molding of certain types ofmechanical goods.

As the press shown herein is the first press adapted for this type ofwork in which mechanically operated closing means is provided, theinvention is' entitled to a substantial scope to cover similar presseswhich utilize the principles of the invention while departing from thedetails embodied in the form shown. For example, the press shown is atoggle operated press in which the upper platen or press head rocks asit is moved to and from its closed position, but the press may operatein a straight line between its extreme positions. Also, the press isillustrated as of thetype in which the lower platen is stationary whilethe upper platen is moved, but the art is familiar with presses in whichboth platens partake of the opening and closing movements and also inwhich the lower platen alone moves, and it would not amount to adeparture from certain features of the invention to apply them topresses of either alternative type.

A complete press with all of the improved features is shown in thedrawings.

Fig. 1 is a side elevation of the press in closed position.

Fig. 2 is a similar view showing the press in fully opened position, theupper mold carrier being elevated. In this view, as in several others,the molds have been omitted.

Fig. 3 is the press at its unloading position, showing how the uppermold is made accessible to the operator by the lowering of the uppermold carrier. V 1

Fig. i is a longitudinal vertical section of the press in closedposition on the line 4-4 of Fig. 6.

Fig. 5 is a front elevation of the right-hand side of the press.

Fig. 6 is a section on the line 6-6 of Fig. 4. In this view is shown inexaggerated form the manner in which blanks of a stiff stock willprevent the mold from closing. 7

Fig. 7 is a section through the press-operating It will also beunderstood that while 4 mechanism on the line 1-1 of Fig. 1, showing oneside of the operating mechanism,'it being unnecessary to show both sidesas the main driving mechanism is merely duplicated on the other side ofthe press.

Fig. 'l is a view showing the upper mold carrier in an intermediateposition.

Fig. 7 is a similar view showing the platen in the position it assumeswhen the press is near its closed position.

Fig. 8 is a plan view of the press.

Fig. 9 and 9 are a longitudinal section and a plan view, respectively,showing the strain mechanism which controls the progressive closing ofthe press as the resistance set up by the stock relaxes.

Fig. 10 is a diagrammatic view showing a typical path followed by theupper platen during a curing cycle.

Fig. 11 is a side view of one of the main crank gears, in this case theright-hand crank gear, showing the limit switch operating means for thepress motor'.

Fig. 12 is a section on the line Fig. 11.

Fig. 12 is a detail section on the line I2 -l2 of Fig. 11.

Fig. 13 is a longitudinal section and Fig. 14 a transverse sectionthrough that portion of the timer switch which controls the periodduring which bumping occurs.

Fig. 14 is a section on the line Hi -44 of Fig. 13.

Fig. 14* is a fragmentary view showing the position of the timer switchparts during bumpmg.

Figs. 15 to 20 inclusive are diagrams of typical electric wiring foraccomplishing the several steps in the preferred operation;

Fig. 15 shows the condition of the circuits when the press is fullyopened; Fig. 16 when the press is overloaded and the closin movement hasbeen arrested by the resistance of the stock; Fig. 1'7 when the press isfully closed; Fig. 18 when the press is being opened to bump the molds;Fig. 19 when the press is closing from bumping; and Fig. 20 shows thecondition of the circuits when the pres is running, the full lineposition of the starting switch showing its position during the closingmovement of the press and the dotted line showin its position duringopenin movement.

Fig. 21 is a diagrammatic view showing the arrangement of the limitswitch control opera- .The platen movement In order to explain moreclearly the many features of press operation, reference will first bemade to Fig. 10 which shows in diagram a typical path followed by theupper platen of a press equipped with all of the controls to give boththe follow up and a subsequent bumping operation. There is no attempt inthis View to show actual dimensions of platen travel.

In Fig. 10 the location of the upper platen in its fully opened positionis indicated by the line a and in its fully closed position by the lineb. The line 0 represents the initial closing movement of the press. Theseries of steps d represent the successive pauses and advancements whichoccure during the follow up as the closure of the press is interruptedby the resistance of the stock. Three successive steps are illustrated,but the number of steps may be greater or less, depending upon the speedat which the stock softens under the combined effects of heat andpressure. The limits at which the press stops and then resumes itsclosing movement are determined by the adjustment of the strain deviceto be more fully described, but by reference to the wiring diagrams(Figs. -20), it will be seen that 800,000 lbs. has been selected as theresistance at which the press stops its closing movement and 500,000lbs. at which it resumes its closing movement.

The offsets e, which occur after the press is closed and which usuallyoccur at the fore part of the curing period, represent the movement ofthe platen as the mold is cracked during the bumping operation.

At the end of the curing period, represented by the left-hand end of theline b, the upper platen rises along the line f until it reaches thelevel g, which corresponds to the position of Fig. 3. It remains in thatposition until the operator has removed the articles which cling to theupper mold section and swabs that section; then the operator presses thestarter button and the platen follows the line it until it reaches thelevel a when it comes to a full stop ready for removing articlesfrom'the lower mold section, swabbing the lower mold and reloading.

The press construction The press is carried by two heavy plates, one oneither side of the press and indicated as a whole by the numeral I. Themain body of each plate is indicated at i and the space between theplates houses the reversible motor indicated at 2 and the driving gear,to be described. Forwardly, the plates I are flared outwardly along theVertical lines I and are lowered in height so that at i the forward endsof the plates form the support for the lower stationary platen. Alongtheir lower edges the side plates are welded to horizontal foundationplates 3.

In the vertical portions l of the side plates are located the bearings 6for the main shaft of the press, indicated at 8. Below the shaft 8 andlocated in bearings 9 in the side plates is the drive shaft M (Fig. '7).This shaft H3 is keyed to a worm gear l2 which meshes with a worm (notshown) driven by the motor 2. The driving gears are enclosed in ahousing indicated at I3. The ends of the shaft iii are keyed to pinionsM which mesh with internal gears cut in the inner rims of large drivinggears i5 welded to hubs IE on the ends of the shaft 8 by face plates ll.One of these gears acts as a means for controlling the limit switcheswhich stop the motor when the press is fully opened or fully closed. Therighthand gear has been selected for this purpose and will be describedmore in detail later. The main gears 55 rotate in the direction of thearrow m in closing and in the direction of the arrow n in opening (Fig.1).

To the face plate of each gear and. surrounding the hub i5 is welded acrank arm in the outer end of which is formed a bearing sleeve 22 whichprojects through the plate ll and is braced to the hub it by a weldedplate 23 (Fig. 12).

Pivotally mounted in each bearing 22 is the lower end of a link 25, theupper end of which projects between and is pivoted at 26 to two parallelplates 27. Each pair of plates 21 is located at the sides of and weldedto the upper ends of one of the main toggle arms indicated at 30.

These arms 30, located at opposite sides of the press, constituteelements of the toggle by which the press is opened and closed and bywhich the immense pressure is exerted on the molds. These arms are madeof a very heavy steel which, however, has the property of stretchingslightly under the very heavy tension which is exerted as the moldsclose together on the stock. The arms are identical except that one,here shown as the right-hand arm, has been selected to carry the strainresponsive device by which the closing of the press is arrested when theload on the press mechanism reaches the predetermined safety limit. Thedrawings also show the additional controls by which the follow up may besecured, if this refinement is adopted.

Across the upper ends of the arms 30 and pivotally mounted in bearings3| therein is the heavy yoke 33 from which depend the parallel arms 34in the lower ends of which are journaled the heavy transverse shafts 35.The yoke 33 constitutes the second element of the toggle mechanism30*33. The ends of each shaft 35 enter bearings formed in two verticalparallel plates 38 and 39 and are fixed by straps Bl to the plates 38.The plates 39 which are located inwardly of the press are substantiallytriangular, as shown in Fig. 4, but the outer pair of plates 38 areformed with forwardly extending portions marked 38 which form thebearings for the rocking upper mold carrier, to be described. Welded tothe lower edges of the four plates 38-39 is the fixed upper platen 40. Acover plate 4| is mounted over the outer edges of the plates 38.

The lower end of each arm 30 is provided with a transverse bearing 42,the arm being reinforced at this point by plates 41-3 welded about thebearing. A transverse beam 45 mounted in openings '36 in the side platesI is provided with trunnions 48 received in the bearings 42. The beamforms the anchorage for the lower ends of the arms 30 and on its upperside is seated a heavy ring-shaped sleeve 50 which constitutes the sup"port for the loweror stationary platen 52. This platen is cored as shownfor the circulation of steam by which the requisite heat is applied tothe lower half of the mold, indicated at 5 1. This mold section, whichis removably secured to the stationary platen in the usual manner, isprovided with cavities for the goods to be cured and, in accordance withthe usual practice, this is normally a multiple cavity mold.

As the mold sections require accurate adjustment in order that they mayproperly meet when the press is fully closed, the sleeve 56 is threadedexternally and the platen 52 is attached to .a' second sleeve 55 spacedfrom the sleeve 50 and threaded internally but in the oppositedirection. An intermediate internally and externally threaded sleeve 56engages the threads on the inner and outer sleeves and is provided withring gear 58 which meshes with an operating and adjusting pinion 60mounted on one corner of the transverse beam '55. The platen isprevented from turning by any suitable means which may be a guide on thesleeve 55 and a guide rail extending from the left-hand side plate asindi cated at 62 in Fig. 4. The mechanism just described forms aconvenient means for securing accurate adjustment between the two moldsections.

In order to provide for accurate alignment of the platens, each arm 35carries near its lower end an adjusting screw 65, the end of whichreduced and carries a footer 66 which bears againsta finished surface.67 formed in the side plateand of sufficientextent to permitthe footerto move over the plate from full open to'f-ull closed press positions.

The upper platen mechanism In order to guide the upper platen in itsmovement while the press is opening and closing, an arm '10 is attachedto the upper platen and extends rearwardly to a point above the shaft 8.The detailed construction of this arm does not need to be described, itbeing sufficient to state that, in the form shown, it is made up of anumber of plates welded together and welded at its forward end to theupper platen. The rear end of the arm if! is forked to provide bearingsfor two shafts "H, each of which is held in position by a strap 72attached to the inside of the forks. The outer end of each shaft carriesa guide shoe I which is movable vertically in slots 16 cut in the sideplate I (see Fig. 7).

When the press is fully opened, as shown in Fig. 2, the shoes 75 are atthe bottom of the slots, but as the toggle links 33] approach theivertical position, the shoes i5 move upwardly in the slots momentarilyand then drop down to approximately their original position. This combination of mechanical movements causes the platen i!) to rock from itstilted position shown in Fig. 2 to a position in exact parallelism withthe lower platen as the press approaches its closed position andmaintains this parallelis until the press is fully closed.

A further factor governing the movement 01' the upper platen ii) is oneof the two cam guides which are indicated as a whole by the numeral 8G.In the press as shown the cam guide for the platen 4B is on the left. InFigs. 2 and 7 the side arms 3!] are broken away to show theconfiguration of the cam plates, which is the same for both plates. Eachcam guide is a flat plate attached to the inside of an arm 30 by boltsti Cut in each plate is a cam guideway of the peculiar shape shown inthe several views.

At the rear left corner of the platen so is a depending bracket 83 inwhich is mounted a roller 84 which moves in the left hand cam guide.This surface starts at the recess p (Fig. 7 continues as a comparativelystraight surface 30 then has bulge p and terminates in the recess :0When the press is fully closed, the roller 84 rests at 70 and when it isfully opened, it rests at p the intermediate cam surfaces holding theplaten =16 in its proper position during the entire cycle of opening andclosing the press.

It will be noted that the member 48 which has been referred to as theupper platen, is, in reality, .a false platen, the heated platen elementcorresponding to the element 52 being a supple mentary cored platen 88to which the upper mold section 89 is removably attached. Thissupplementary platen is so arranged and constructed that it tiltsdownwardly as the press is opening for the purpose set forth previously.7

For this purpose the supplementary platen is carried by two brackets 90on the outer side of the platen GI! and pivotally supported on theextensions 3E by a transverse shaft 92. The inner right-hand corner ofthe supplementary platen is provided with a roller 9:3 which travelsover the lower portion of the cam groove in the righthand cam plate 39.It will be seen that the rollers 84 and 94 on the moving upper platen 49and the rocking platen 88, respectively, do not interfere because theymove in different cam plates. When the press is fully closed, the roller94 rests on the recess p 'of its cam plate and this brings the twoplatens together. As the press starts to open, the roller 94 moves overthe surfaces p -p of the cam groove which are parallel to the surfaces pand p and this keeps the platens together and parallel to the bottomplaten up to approximately the point shown in Fig. 7*. As the presscontinues its opening movement from this point, the roller 94 followsthe descending surface 70' until it reaches the recess 12 which is thetime that the press is partially open at theline g in Fig. 10. At thispoint the opening movement stops and the upper mold is presented to theoperator as shown in Fig. 3.

After the operator has removed the articles from the upper mold, hecauses the press to continue its movement toward the full open position.During movement of the rocking platen 88 from unloading to full openposition, the roller 94 is in contact with the vertical arched surface72 of the cam groove and the reaction created thereby lifts the rockingplaten 88 until the roller 94 rests in the recess p in alignment withthe roller 84, bringing the two platens together again at the top of theopening movement, as shown in Fig. 2. On closing, the roller 9 followsthe cam surfaces p to 17 the latter end of the movement bringing therocking platen against the fixed platen 40 as the mold sectionsapproach.

In molding certain types of goods which do not tend to stick in theupper mold section, the platens 40 and 88 may be bolted together, asshown at 89 in Fig. 2, in which case these two platens move as a singleelement.

The press arresting and "follow up mechanisms The means by which theclosing movement of the press is arrested when the resistance offered bythe stock approaches the safety limit will now be described. As thecomplete press in shown, this will also include the means by which thefollow up is obtained.

The underlying principle of the control mechanism is that a press of thetype shown herein, or, indeed, any other press, is subjected to highstresses when it is attempted to force the press to close againstexcessive resistance such as caused by many blanks of a stiff stock.Such a condition is illustrated in Fig. 6 where one of the blanks ofuncured stock Z is shown between two partially closed mold sections. Theresistance to further closing offered by one blank is multipled as manytimes as there are separate mold cavities. This resistance is reflectedin the stretching or yielding of the toggle links, levers and otherparts of the press under the heavy load. Even such heavy and apparentlyunyielding elements as the toggle links 36 will stretch under loadswhich are created by attempting to close the molds together againststocks such as employed in goods of the types specified.

It should be distinctly understood that other parts of the press thanthe links 39 exhibit the property of stretching or yielding under suchextreme stresses and while an element 30 has been selected for thepurposes of the present description, it is not intended to confine theinvention in its broader aspects to the use of this particular elementas the strain responsive element which controls the closing movement ofthe press.

Referring now to the particular means shown herein, the side links 3!!of this particular press W111 exhibit the property of stretching severalthousandths of an inch when the load between the yoke 03 and the lowerbeam 45- is between 800,000 and 500,000 lbs. This is sufiicient tooperate micro-switches mounted on a side arm to stop and start the pressmotor at the stated limits, respectively.

Either side arm. 30 may be selected for the pur pose and the drawingshows the strain responsive elem nts located on the right-hand link.

Referring particularly to Figs. 9 and 9 the front edge of the arm 30 isprovided with an open groove extending the length of the link and inthis groove lies a long steel bar I00 which is pinned at its lower endto the side arm by the pin IOI. The location of this pin is shown inFig. 5. The groove is slightly wider and deeper than the bar so that thebalance of the bar I00 is free of the arm and may float thereon. It willbe seen that as the arm stretches under the load imposed thereon orrelaxes as the load is relieved, any point near the upper end of the barwill shift over the surface of the arm. This rela tive movement betweena point on the arm and a point on the bar is utilized to actuatemicroswitches which stop and start the motor in response to the strainsexerted on the press and reflected in the elongation of the side At apoint near the upper end of the bar I00 is welded a cross piece I 02 andon one side of the bar there is threaded in the cross piece theadjustable stud I04 which is headed toward the top of the arm 30, and onthe other side of the bar is the threaded stud I05 which is pointedtoward the lower end of the arm. Stud I04 is adapted to contact theoperating button I05 of a micro-switch I01 and the stud I05 is adaptedto contact the button I08 of a second switch I09 as hereinafterdescribed. Both micro-switches are attached to the arm 30. A cover plateH0 is secured to the arm 30 to house the switches and a conduit [I2 isalso mounted on the arm and serves as a conduit for the wires which leadfrom the switches.

The switch I01 is the low limit switch, that is to say that when thisswitch is closed the circuits to the press motor will be maintained andthe press will continue to move. The switch I09 is the top limit oroverload switch, that is to say that when this switch is opened thecircuits to the motor will be open and the motor will stop, halting theoperation of the press. When the arm 30 is not under excessive strain,both switches I01 and I09 are closed. Such a condition is shown in Fig.15.

When, however, the strain on the link passes its predetermined lowlimit, here shown as 500,000 lbs., the switch I01 has been moved by thelengthening of the arm 30 to such an extent that the switch I01 has beenopened. The stud I05 is set so that it does not come into contact withthe button I08 of the high limit switch until the load on the linkreaches the predetermined high limit, which, as noted above, is selectedin this case as 800,000 lbs. During the period that the resistance isbuilding up from 500,000 to 800,000 lbs. the press motor is operating bythe current provided through the switch I09. When, however, theresistance reaches the high limit all current to the operating motor 2is out off by the opening of the switch I00. When the overload switchI00 is shifted to open position a secondary or holding circuitassociated with the switch I09 is closed through relay R, line I39,switch I09, line I45, safety switch M1, line I40, switch I26, line E40,to switch I4! and return line I50, which holds it in open position untiloperating conditions are restored in which switch I00 is desired to beclosed. Such a holding circuit is shown in the various figures (15 to20) at I I0, and includes a contactor which is closed by relay R as soonas switch I09 reaches its open position, as shown in Fig. 16. This isthe only position of switch I00 in which the holding circuit H0 isoperative. When the resistance in the arm drops to the low limit, say500,000 lbs, the stud I04 strikes the button I00 which, closes theswitch I01 and the motor is again started up. The complete operationrequires that the high limit switch be again closed and this isaccomplished because the switch I00 is biased to closed position andbecause the holding circuit M0 for that switch is shunt circuitedthrough a line II2 which connects the circuit H0 to the pole of the lowlimit switch 801, and thereby shortly thereafter closes switch I09 withswitch I01. a

' This closing of switch I01 provides a circuit through line I45, switchI01, shunt line H2, holding circuit II 0, line I46, safety switch I41,line I48, switch I26, line I49, to switch MI and return line I50. Inline I is a coil I52 which is now being energized to close the gapbetween the plates of sticker switch I54, which plates are quicklyclosed but which are subject to delayed action when opening. As soon asswitch I01 is closed and the circuit is established through shunt lineIIZ, the effect of the relay R on the holding circuit I I 0 is weakenedand gradually the latter circuit becomes non-effective, at which timeswitch I09 quickly returns to closed position due to its biasedarrangement. At the moment that holding circuit II 0 becomesnon-effective and switch I00 returns to closed position, the circuitwhich included holding circuit III] is broken, thus temporarilyrendering coil I52 incapable of acting on the plates of sticker switch154. But since the latter plates are delayed in their opening action,switch I00 returns to its closed position before these plates can open,and a new circuit is established through line I45, sticker switch I54,line I55, switch I09, line I40, safety switch I41, line I48, switch I20,line I40 to switch I4! and return line I50. As soon as this new circuitis established, coil I52 is again being energized to hold the plates ofsticker switch I54 in closed position, and as hereinafter explained, theclosing of sticker switch I54 completes the power circuit to the motor2, to continue the closing movement of the press.

It will thus be seen that when the resistance to press closing reachesthe upper limit, the press will cease to operate. If the follow up isnot to be used, this overload switch only is employed and the restartingof the motor may be done manually. If, however, the automatic follow upis desired, as in the preferred form shown, the motor will beautomatically connected to its source of power when the resistance dropsto the predetermined low limit. This is due to the fact that theoverload switch is not effective to stop the motor until the resistancereaches the high level, and during the period that the resistance isdropping from that high level to the low level, the motor is idle, butstarts up again when the low level is again reached.

The limit switches Presses of the type shown herein are provided with apush button S which normally remains in the neutral shown in Figs. 15 to19. This button is pressed by the operator to start the press operationswhen the molds are fully loaded and the play. The timing device may beof any well known type, that shown in applicants prior Patent No.2,321,326, June 8, 1943, being adaptable for the purpose. In the pressillustrated here this device is operated by a constant speed motor whichoperates continuously, the timing mechanism therein being connected tothe motor by a clutch operated concurrently with the actuation of thestarter button S. The timing motor, when engaged, operates a cam diskwhich, after a predetermined rotationmovesthe starter button S to aposition where it operates a contactor to close the power circuit andthe motor now rotates in reverse direction to open the press. Theposition of the starter button in the two running operations is shown inFig. 20.

In the particular press shown here the timing device is also providedwith a cam which in conjunction with a limit switch performs the bumpingoperation, referred to above, shortly after the mold is fully closed.

The automatic control shown herein further contemplates the use of asecond limit switch operative when the press reaches the unloading or gposition in Fig. to stop the press before it reaches its fully openposition. After the workman has performed the operations duringunloading, he presses a second button S which closes a circuit operatinga contactor to close the power circuit to the motor 2 until thepress isfully opened, whereupon the second limit switch again comes into actionto stop the press.

The means selected to control the stopping of the press at the open andclosed positions and also the bumping operation is one of the main gearsI5, in this case the right-hand gear.

As will be seen in Figs. 7, 8 and 12 the periphery of the right-handgear I5 is provided with three grooves which are indicated, from rightto left, as I20, I2I and I22. Secured to the plate I adjacent thelowerside of the gear in a bracket or housing I24 are three switchesI25, I25 and I2? provided with push buttons which are in alignment withthe several grooves respectively. The order of the switches isimmaterial but for the present purpose the switch I25 may be consideredas the opening limit switch which breaks the circuit to the motor whenthe press has reached the unloading position and again when the pressreaches its fully opened position. The switch I25 is the closing limitswitch which arrests the movement of the press when it reaches its fullyclosed position. The switch I2! is the bumping switch which participatesin the repeated opening and closing of the press during the cure. Theseswitches are also marked IM, 2M, 3M respectively on the wiring diagrams.

These several switches are operated by blocks set in the proper grooveson the gear so that the switches are operated when the press is in itscor-- rect position for the switches to function. As shown in Fig. 12each block is split from its under-surface and a threaded expansionscrew I28 is received therein by which the block is clamped in itsproperly adjusted location on the periphery of the gear I5. The locationof. 16 3.

ISO

12 several switch operating blocks is shown in Fig. 1 and their timedrelation is shown in Fig. 21. In the groove I20, which coincides withthe opening limit switch is set a block I30 which in Fig. 1 is at aboutthe 12 oclock position around the gear. When the press reaches theunloading position, however, as shown in Fig. 3, this block is at thecontrol box I24 and has opened the switch I25. The block for againactuating the switch I25 when the press is fully opened is indicated atIsl in the groove I20. In Fig. 1 this block is at about the 10 oclockposition but reaches the control box when the press is fully opened asshown in Fig. 2.

The block for actuating the switch I20 for stopping the motor when thepress is fully closed is located in the groove I2I and is designated bythe numeral I32 and is coincident with the control box I24 when thepress is fully closed, as in Fig. 1.

The block I33 for depressing the bumping switch I2? is set in the grooveI22 and is spaced somewhat in advance of the block I32 depending uponthe distance to which the mold is to be opened or cracked duringbumping. Due to the fact that the bumping circuit is normally open, thisswitch is effective only during a por tion of the curing cycle and onlyfor a short period after the press is actually closed.

In the several wiring diagrams the direction in which the switches aremoved by the several blocks on the main gear I5 is shown by the arrowsapplied thereto.

It is unnecessary to describe the construction and operation of thetiming mechanism for devices of this nature are well known in the artand are standard equipment made and sold by a number of concerns. Thetimer is operated by a synchronous motor T which is shown in the various wiring diagrams on a secondary circuit I40.

which receives current constantly so that the timer motor iscontinuously operated. If it is desired to by-pass the timer for specialoperations when the timer control is not desired, a throw-out switch I4Iis provided. The relay R for the timer motor is located in a line I39extending from the overload switches to the line It may be noted at thispoint that the circuits for the various controls are shown as 11 0 v.,current being supplied from the main 440 v. line to the motor T througha transformer I42. It should also be noted that the power circuit, asdistinct from the control circuit, of the motor 2, is separate from thecircuits shown.

Assuming that the press is fully opened and the circuits are in thecondition shown in Fig. 15, and the mold cavities are filled, theoperator presses the spring loaded starter button S to the right, whichstarts the motor 2, and at the same time connects the motor T with thetiming devices.

As shown in Fig. 15, the movement of the switch S to the right, i. e. tothe dotted line position in Fig. 20, closes the line I45, through theswitch I25, line I 49, switch I4I and return line I50. In the line I45is the coil I52 which is now being energized to operate a closingsticker switch I54 which completes the power circuit to the motor 2, andalso closes the gap between the plates of switch I54 in the controlcircuit. This is sufiicient to cause the block I3I to leave theswitchI25 which now shifts from the position shown in Fig. 15 to that shown inFig. 20 and the current flows from line I45 through switch I54,

line I55, the overload switch I69, line I46, safety switch I41, lineI48, switch I26, to the line I49, switch MI and return line I55. Duringthe time that coil I52 is energized, it enables the sticker switch I54to complete the circuit through the shunt line I55 so that current ismaintained in the motor closing circuit during the closing operation andthe push button may be released immediately when the press has started,said push button returning to its neutral position indicated by the termRun in Fig. 15.

The operation or" the overload switches I61 and I89 has already beendescribed, it being noted here that the line I55 is connected to onepole of the overload switch I59 and that the low limit switch isconnected to the line I45.

When the press reaches its fully closed position the switch I26 is movedby the block I32 to open position as shown in Fig. 17 and the motoroperating circuit is broken at this point.

When the full time for curing has elapsed the timer acts upon thestarter button S and moves it to the left dotted line position shown inFig. 20. The clutch in the timer is disconnected at the same time.Current now flows over the line I56, through the switch I25, line I49,switch I4I to the return line I55. In the line I50 is the coil I 62which is being energized to operate the opening sticker switch I55 whichcompletes the power circuit to the motor 2 to start the opening of thepress, and also closes the gap between the plates of switch I63 in thecontrol circuit. The sticker switch I63 is located in the line I 54which connects with switch I21 and line I65 to the switch I25. block I36opens the switch I25 when the press is at unloading position, whereuponthe conditions of Fig. 15 are reproduced, switch I26 having returned toits initial position as the press began its opening movement.

After the workman has performed the necessary operations at theunloading position he presses a second spring loaded button S which isnormally across the line I45 but which is now moved to the dotted lineposition shown in Fig. 20. This connects the line I16 with the line I64. The line I15 is also connected with the line I46 at the safety switch141, and the circuit is completed through switch I25, line I49, switchMI and line I55. A brief pressure on the switch S is sufficient to startthe motor by closing switch I 63 to operate the press to move the blockI311 off the switch I25 permitting the latter to return to its Fig. 20position. Movement of switch I25 to its Fig. 20 position re-establishesthe original press opening circuit through switch I25, and the return ofbutton S breaks the circuit that included line I16. Thus, normal openingof the press is resumed and continues until the block I3I again stopsthe press by opening the switch I25 at the fully opened position.

The safety switch I41 is moved only in case of accident during closing.Devices for throwing safety switches are well known and need not bedescribed or shown. When moved in the direction of the arrow appliedthereto in the various wiring diagrams, it reverses the direction of themotor instantly. These circuits are clearly shown and need not bedescribed.

A push button switch I12 is located at any convenient point, here shownas in the common return line I56, by which the operator can stop themovement of the press at any point without preventing its continuedoperation when the button is released.

This condition continues until the The bumping operation The openingbumping operation is performed through a special switch I15 which islocated in a circuit which opens the press. This switch is open duringthe entire period of press operation except during the bumpingoperation. In conjunction with this switch the switch I21, which isactuated by the block I33, brings the press back to its closed position.

This special bumping circuit switch is indicated at I15 in the wiringdiagrams and its actual position and construction is shown in Figs. 13to 1 1 As shown, it connects the line I64 with a line I16 which leads toa pole I11 of the switch I26. It will be seen by an inspection of Figs.17 and 18 that when the press is fully closed and the switch I15 isclosed an opening circuit is provided through these instrumentalities.This opening circuit includes coil I62, line I65, line I64, switch I15,line I15, switch I25, line I49, switch MI and return line I55. A secondcircuit leads from line I49, through switch I25, line I65, switch I21,to line I64, which circuit will be established as soon as the plates ofswitch I63 move together by energization from coil I52. As soon asswitch I15 is closed as in Fig. 18, coil I62 will be energized tooperate switch I53 to start the motor to open the press and to move theplates of switch I63 together to complete said second circuit. As soonas the press begins to open, block I32 moves away from switch I26 andthe latter returns to its open position (Fig. 19) and breaks the openingcircuit that included switch I15, without, however, aifecting the saidsecond circuit which permits the press to continue its opening movement.Since, in this second circuit is located the switch I21, when the blockI33 strikes this switch the latter moves to its Fig. 19 positionbreaking the second circuit and arresting the opening movement of thepress. In its Fig. 19 position, switch I21 connects line I85, leadingfrom line I45, with line I55. In line 585 is a spring biased stickerswitch I82, the plates of which are held apart by the energization ofcoil I62 during the opening of the press, but as soon as the openingcircuit is broken and coil I52 de-energized, the spring action closesthe plates of switch I62. Thus, a temporary closing circuit is set up(Fig. 19) that includes coil I52, line I45, line I85, switch I82. switchI21, line I55, switch I69, line I46, safety switch I 41, line tilt,switch I 26, line I59. switch I4I and return line I55. As soon as thisterm porary closing circuit is established, coil I52 is energized tostart the motor 2 to close the press and the plates of switch I 54 aremoved together to connect line I55 directly to line I55. As the pressmoves to closed position, block I 33 will move out of contact withswitch I21 and the latter will return to its Fig. 18 position, breakingthe temporary closing circuit, but since the regular closing circuit hasbeen re-established through switch I54, the closing movement of thepress continues until the switch 526 is again moved by the block I 32from position shown in Fig. 19 to that shown in Fig. 18, whereupon theclosing circuit is broken and the opening circuit re-established.

It will be seen, therefore, that during the period that the switch I15is closed, as shown in Figs. 18 and 19, the press will oscillate betweenfully closed position and partially open position over a spaceddetermined by the setting of the block I33. This is shown in Fig. 21 asthe space between the area marked I33 and the right-hand area markedI32.

The time during which the switch I15 is closed and, therefore, theperiod during which bumping takes place and consequently the number ofbumps, is controlled by the timer as will be more fully described,reference being directed particularly to Figs. 13 to 14 In the line I19is a snap switch I84 which can be thrown so as to by-pass the bumpingswitch altogether in the event no bumping is desired. An overloadcircuit breaker I83 is located at a convenient point in the circuits.

The timer is located at any point convenient to the operator as hestands at the press. The timer box or casing, which houses the motor Tand the various control elements operated thereby, is indicated at I85.It is built with a compartment I86 which houses the bumper controlmechanism. The main control shaft of the timer is marked I88, this beingdriven at slow speed by the motor T when the operating clutch is engagedso that it completes a full revolution with each cycle from the start ofthe press on its closing movement to the point where it begins itsopening movement concurrently with the open ing of the clutch.

On the shaft I88 is a flange I89 against which the cam, indicated as awhole by the numeral I99, is located. This cam is preferably composed oftwo fiat plates or disks rotatable relatively to one another about theshaft I88 and held in adjusted position by a nut I9I on a screw threadedportion of the shaft which presses against the block I92 to hold the twodisks in their proper adjusted position. The cam I99 is made up of thetwo disks I90 and I90 the working edge portion of the latter having aslightly greater radius than the radius of the former.

The switch I15 is normally open, ,as indicated in all of the wiringdiagrams except Figs. 18 and 19. Over the switch I15 and normall out ofcontact with it is the horizontal arm of an angular switch operatinglever I94 pivoted at I95 in the housing. The vertical arm of lever I94extends to a point adjacent the cam I90 where it is forked as shown inFig. 14* and carries a transverse pin I96. This pin is located in thepath of an adjustable set screw I98 carried in a lug I99 formed on theouter end of a lever 200. The lever 200 is provided on its outer endwith 2. depending fork I in which is mounted a roller 202 which lies inthe path of the composite cam I99.

When the bumping operation is inactive the lever 200 rests with one ofthe forks 20I on the top of a wall of the housing as shown in Fig. 14,at which time the edges of the cam disks I90 and I90 are out of contactwith the roller 202. Shortly after the cam I90 starts to move in thedirection of the arrow in Fig. 13, as it will when the timer starts inoperation, the high part of disk I90 passes under the roller 202 andlifts the lever 209 to the point where the end of the screw I98 strikesthe pin I99 which rocks the lever I94 and closes the switch I15. Thebumping operation'will therefore continue as long as the roller 202 isin contact with the cam disk I 90*. This position of the parts is shownin Fig. 19 and will continue for a period dependent upon the relativepositions of the disks I90 and I90.

When the shaft I88 has rotated so that the disk I90 reaches the roller202 the screw I98 will pass above the pin I96 and the lever I94 willdrop down again to its normal position opening the switch I15 andbumping will cease.

. The press being in the position shown in Fig. 2,

and the molds being properly cleaned and lubricated, and the cavities inthe lower mold being filled with blanks of uncured stock, the operatorpresses the button S which starts the press on its closing movement. Thesame operation also connects the timing motor with the various movabletime control devices. The actuation of the starter button engages thesticker switch I59 and the motor continues its movement after the buttonS is released.

As the molds close on the stock, the resistance offered by the stockincreases as explained, but the press continues its closing movementuntil the resistance reaches the predetermined high level selected as800,000 lbs, at which point the closing movement of the press isarrested by the operation of the overload switches shown in Figs. 9 and9 This is due to the relative movement between the bar I09 and the arm39 on which it is carried, the latter stretching under the load exertedby the resistance of the stiff stock. The circuits to the motor arebroken in the manner described. If the follow up is used the press willremain immovable until the stock has softened sufhciently to reduce theload on the arms 30 to the selected low limit, here 500,000 lbs,whereupon the closing circuit will be reestablished and the press willresume its closing movement until the resistance again reaches the highlevel. This intermittent closing will continue until the press is fullyclosed.

When the press reaches its fully closed position' the block I32 open theclosing circuit and the press remains closed during the perioddetermined by the timer, except for the bumping operation, if this isemployed.

As explained, the bumping operation occurs only during the interval thatthe cam disk I90 keeps the bumping circuit switch I15 in operation for asufiicient period to release the gases from the molds. The number ofdistinct bumping operations is determined by the time interval duringwhich the cam surface I90 is in contact with the bumping switch lever200.

When disk I90 comes into play bumpin ceases and the press remains closeduntil the timer moves the switch S to the dotted line position of Fig.20, whereupon the timing motor clutch is disconnected and the motor 2 isreversed and the press starts its opening movement. This movementcontinues until the block I30 opens the switch I25 which arrests thepress in the position shown in Fig. 3.

During the opening movement the movable platen 88 has, through theaction of the cam plate 80, dropped to the position shown in Fig. 8

so as to provide easy access to the upper mold section. When the uppermold is freed of articles adhering thereto and is properly swabbed theoperator presses the button S and the press resumes its openingmovement, the platen 88 being picked up and restored to parallelism withthe platen 40. When the press reaches its fully open position the blockI3I opens the circuits through the switch I25.

During the travel from open to closed position and. return the upperplaten 40 has been guided in its movement by the arm 10 and by the cam80. As the two platens approach their closed position the movable platen88 is restored to its position in contact with the platen 49. As theplatens near their final closed position the upper platen is parallel tothe lower platen and during the final closing movement the upper platenmoves in a straight line. This action is assured by the 17 joint actionof the various upper platen guiding means.

It will thus be seen that a wholly new and novel press has been designedwhich makes it thoroughly practical to cure goods of the types specifiedin mechanically operated presses. While the description and drawingshave been detailed so as to give a full exposition of the best known andpreferred form of the invention, it is not intended to limit theinvention to the specific embodiment shown and described. The straingage as the elements shown in Figs. 9 and Q are sometimes called is anovel means of controlling a mechanically operated press so that itadapts itself to the particular type of molding operations which thispress is intended to perform without endangering the press. When thefull complement of switches shown in these views are employed the presssimulates the follow up action of a hydraulic press.

While the various elements of the press shown cooperate in combinationto achieve the results specified in the most efficient manner, it willbe obvious that the several elements may also be employed individuallyand it is not intended that the invention shall be limited to thesimultaneous .use of all of the features shown and described.

What is claimed is:

1. In a press of the character described, a base, a mold sectionfastened to said base, a toggle mechanism for opening and closing thepress comprising an arm pivoted to the base, a swinging link pivoted onthe end of said arm, a platen pivoted on the end of said link, aswinging moldsupport mounted on a horizontal axis on the platen and towhich a'second mold section is fastened, a cam secured to the arm, and acam follower on the mold support and movable over the cam by theoperation of the toggle mechanism, said cam being shaped so as to raiseand lower the mold support during the closing and opening of the pressrespectively.

2. In a press of the character described, a base, a mold sectionfastened to said base, a toggle mechanism for opening and closing thepress comprising an arm pivoted to the base, a swinging link pivoted onthe end of said arm, a platen pivoted on the end of said link, aswinging moldsuppcrt mounted in a horizontal axis on the platen to whicha second mold section is fastened, a cam secured to the arm and a camfollower on the mold support and movable over the cam by the operationof the toggle mechanism, said cam being shaped so as to lower themold-support during a part of the opening movement of the press and toraise the mold-support during the final portion of the opening movement.

3. A press for molding plastic materials comprising a base, a moldsection attached to the base, a movable platen above the base, means toraise and lower the platen to open and close the press, a mold supporthinged to the platen, a second mold section carried by the support,means operative during the opening of the press to rock saidmold-support to present the mold at an inclined angle with respect tothe platen when the press is partially open and to move the mold supportinto parallelism with the platen at the end of the opening movement, andmeans to arrest the opening movement of the press in said partially openposition.

4. A press for molding plastic materials comprising a base, a moldsection attached to the base, a movable platen above the base, means toraise and lower the platen to open and close the press, a mold supporthinged to the platen on a horizontal axis, a cam and a cam followeroperative during press operation to lower the mold support away from theplaten while the press is in partially open condition and to move themold-support into parallelism with the-platen when the press is ateither limit of its movement and means to arrest the opening movement ofthe press when the press is partially open and the mold-support is in alowered position.

5. A press for molding plastic materials com-- prising a base, a moldsection attached to the base, a movable platen above. the base, means toraise lower the platen to open and close the press, a mold supporthinged to the platen on a horizontal axis, a cam and a cam followeroperative during press operation to lower the mold support away from theplaten While the press is in partially open'conditicn and to move themold-support into parallelism with the platen when the press is ateither limit of its movement, and means to arrest the opening movementof the press when the press is partially open and the mold support is ina lowered position and to arrest the press at either extreme of itsmovement.

6. A press for molding plastic materials comprising a base, a moldsection attached-to the base, a movable platen above the base, means toraise and lower the platen to open and close the press, a mold supporthinged to the platen, a second mold section-carried by the support,means operative during the opening of the press'to rock saidmold-support to present the mold at an inclined angle with respect tothe platen when the press is partially open and to move the'mold supportinto parallelism with the platen at the extremes of the opening andclosing movements, and means to arrest the opening movement of the pressin said partially open position.

7. A press for the treatment of plastic stocks having relatively movableplatens, complementary mold sections carried by the platens, a motor,mechanical connections operated by the motor to close and open thepress, mechanism carried by a member of the press responsive to thestrain in said member exerted by the resistance of the stock on approachof the platens prior to complete closure thereof to arrest the motorwhen said strain reaches a predetermined value, and means responsive toa decrease in the strain in said member to cause the motor to resume itscljosing movement.

8. A press for the treatment of plastic stocks having relatively movableplatens, complementary mold sections carried by the platens, a motor,mechanical connections operated by the motor to close and open thepress, said connections including a toggle link extending across themold sections, mechanism carried by said toggle link responsive to thestrain in said toggle link exerted by the resistance of the stock onapproach of the platens prior to complete closure thereof to arrest themotor when said strain reaches a predetermined value, and meansresponsive to a decrease in the strain in said toggle link to cause themotor to resume its closing movement.

9. A press for the treatment of plastic stocks having relatively movableplatens, complementary mold sections carried by the platens, a motor,mechanical connections operated by the mo tor to close and open thepress, said connections including a toggle link extending across themold sections, a floating bar attached near one end to said toggle link,mechanism carried by said toggle link and actuated by relative move-

